Ocean Acidification: More Than Just Corals at Risk

A new study on an array of marine animals shows that they all will suffer in different ways in the acidified oceans of coming decades. That means rising carbon dioxide levels will trigger some profound reshuffling of life in the seas as some species are more hurt than others.

Because some of the carbon dioxide released into the atmosphere by the burning of fossil fuels is sucked up by the oceans, it causes sea water to gradually become more acidic. This ocean acidification, as it’s called, is a separate consequence of humanity’s unbridled carbon emissions, in addition to climate change.

There have been many reports about ocean acidification affecting marine organisms, but the severity of the threat to ocean ecosystems — and we humans who depend on them — is not at all well understood. In a new paper in the journal Nature Climate Change, Astrid C. Whittmann and Hans-O. Pörtner evaluate the scale of this threat by analyzing how sensitive animals are depending on which group they belong to: corals, echinoderms (e.g. sea urchins and star fish), molluscs (e.g. clams and snails), crustaceans (e.g. crabs and lobsters) and fishes.

In all, they looked at 167 studies that tested 153 species under a wide range of carbon dioxide concentrations. They found that corals, echinoderms and molluscs are more sensitive to projected carbon dioxide increases by the year 2100 than are crustaceans. More worrisome, however, is that fish larvae maybe on the more sensitive end of the spectrum.

Over all, the variety of ways that animals respond to ocean acidification, together with evidence from the fossil record, suggest that ocean acidification will be a major driver for change in ocean ecosystems in the 21st century, assert the researchers. So it’s likely that there will be long-term shifts in species we see occupying different niches in the oceans.

What does that mean for the fisheries and the seafood we eat? That’s pretty hard to say at this point. About the only thing that’s certain is that there will be changes — huge changes — to the seafood section in your store, if there even is one by the year 2100.

Image: Corals are among the many marine animals threatened by ocean acidification. “A” shows a healthy coral reef with living Acropora palmata and good water quality. “B” shows a degraded coral reef with the same species of coral, dead and in murky water. Ocean acidification is rapidly transforming reefs in Puerto Rico and other Caribbean and western tropical Atlantic Ocean regions. Credit: Ryan Moyer/USGS